This invention broadly relates to a medical device, and more particularly a medical device for administering or receiving fluids to or from a patient.
Health care personnel using needles for injecting or for withdrawing blood are subject to serious risk of infection if they are accidentally scratched or punctured by a needle after its use. Such a scratch or puncture carries with it the risk of incurring a viral or bacterial infection.
It is estimated that there are, on the average, 50 to 100 accidental needle stick injuries per hospital per month. It is further estimated that such accidental injuries often necessitate examination and laboratory testing costing between $700.00 and $1000.00 per injury. An infection caused by such an accidental needle stick injury leads to even greater expense and disability.
Because of the substantial risk and cost associated with accidental needle stick injuries, procedures have been developed for disposing of used hypodermic syringes and/or needles. One procedure is to remove the needle from the syringe and dispose of it separately in a receptacle designed for needle disposal. In some cases such removal of the needle requires a special implement, such as a guillotine-like mechanism which severs the needle from the syringe and deposits the needle in a closed receptacle. However, the receptacle and the implement needed to remove the needle are usually not available at the bedside, where many injections are made. Thus, this procedure is inadequate to prevent accidental needle sticks and resulting infection in such cases.
One mechanism for protecting a needle after use is shown in U.S. Pat. No. 4,664,259 to Landis. This patent discloses a container for enclosing a needle after use. The structure of the Landis patent requires a person to manually place the container over the needle after use by pivoting the container onto or about the needle. Such action requires the person to bring his or her fingers into close proximity with the tip of the needle, thus creating the potential for accidental contact with the needle tip. The enclosure provided by the container of the Landis patent does not prevent reuse of the syringe, since a person need only remove the container to once again expose the needle for use.
U.S. Pat. No. 4,676,783 to Jagger et al. discloses an assembly for disabling an intravenous cannula after use. The structure shown in the Jagger et al. patent requires the user to manually withdraw the needle into a cylinder, upon which the tip of the needle is enclosed to prevent accidental contact therewith. This structure is not for hypodermic use, and does not prevent a person from reusing the intravenous cannula.
The present invention overcomes the shortcomings of previous mechanisms and/or procedures for preventing accidental contact with the tip of a needle after use. In particular, an object of the present invention is to provide a structure for automatically or semi-automatically disarming or disabling a needle after use. A further object of the invention is to provide such a structure which automatically or semi-automatically disarms or disables a needle without the user bringing his or her fingers into the vicinity of the tip of the needle. Yet another object of the invention is to provide a structure for automatically or semi-automatically disarming or disabling a needle immediately upon withdrawal of the needle from the patient or even while the needle is still in the patient, so that the tip of the needle is never exposed after withdrawal from the patient. Yet another object of the invention is to provide a structure which permanently disarms or disables a needle after use to effectively prevent reuse of the needle, whether accidental or intentional.
In accordance with the invention, a medical device for administering or receiving a fluid to or from a patient, such as a hypodermic syringe, has a conduit means extending therefrom, such as a needle. The needle has a sharpened end adapted for insertion into a patient for allowing fluid, such as medication, to flow between the syringe and the patient. A disarming means is provided for converting the syringe from an armed condition wherein the sharpened end of the needle is exposed, to a disarmed condition wherein the sharpened end of the needle is covered, so as to prevent contact with the end of the needle after use. The disarming means includes means for urging the syringe toward its disarmed condition, and a releasable retainer means for retaining the medical device in its armed condition during use and for releasing the means urging the medical device toward its disarmed condition after use. In this manner, the syringe is caused to be converted to its disarmed condition after use.
In one embodiment, the hypodermic syringe is provided with an internal silo, and the means for urging the syringe toward its disarmed condition comprises a biasing means, such as a stretched coil spring, tending to draw the needle into the silo. The releasable retainer means comprises a catch or other mechanism for retaining the needle in an extended position, so as to maintain the syringe in its armed condition against the biasing force provided by the coil spring. After the syringe has been used an its contents injected into the patient through the needle, the catch is released, so as to allow the needle to be withdrawn into the silo by the spring and the syringe to be converted to its disarmed condition. Various mechanisms for releasing the catch are disclosed, including semi-automatic mechanisms manually actuable by the user after completion of the injection, as well as automatic mechanisms responsive to movement of the syringe plunger for automatic actuation upon completion of the injection.
In another embodiment, a telescoping sheath comprising a plurality of segments is provided adjacent the hub of the needle. The segments of the telescoping sheath are held in a retracted condition by the releasable retainer means, to keep the needle exposed during use. The means for urging the syringe toward its disarmed condition comprises a biasing means, such as a compressed coil spring, tending to urge the telescoping sheath outwardly toward its extended condition so as to cover and enclose the tip of the needle. The releasable retainer means comprises a gripping mechanism for engaging the end portions of the segments of the sheath to retain the sheath in its retracted condition against the force of the compression spring. After the syringe has been used and its contents injected into the patient through the needle, the gripping mechanism is released so as to allow the segments of the telescoping sheath to project outwardly to their extended condition so as to enclose the needle. In its extended condition, the telescoping sheath covers the tip of the needle after use to prevent accidental contact therewith.
In both embodiments, the releasable retainer means can be actuated either automatically in response to the action of the plunger or semi-automatically in response to manual actuation by the user. The releasable retainer means can be actuated while the needle is in the patient, so that the top of the needle is never exposed after withdrawal from the patient.